.\" Copyright (c) 2006,2008 Joseph Koshy.  All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\" damages (including, but not limited to, procurement of substitute goods
.\" or services; loss of use, data, or profits; or business interruption)
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.\" $Id$
.\"
.Dd August 29, 2006
.Os
.Dt GELF_CHECKSUM 3
.Sh NAME
.Nm elf32_checksum ,
.Nm elf64_checksum ,
.Nm gelf_checksum
.Nd return the checksum of an ELF object
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft long
.Fn elf32_checksum "Elf *elf"
.Ft long
.Fn elf64_checksum "Elf *elf"
.In gelf.h
.Ft long
.Fn gelf_checksum "Elf *elf"
.Sh DESCRIPTION
These functions return a simple checksum of the ELF object described
by their argument
.Ar elf .
The checksum is computed in way that allows its value to remain
unchanged in presence of modifications to the ELF object by utilities
like
.Xr strip 1 .
.Pp
Function
.Fn elf32_checksum
returns a checksum for an ELF descriptor
.Ar elf
of class
.Dv ELFCLASS32 .
.Pp
Function
.Fn elf64_checksum
returns a checksum for an ELF descriptor
.Ar elf
of class
.Dv ELFCLASS64 .
.Pp
Function
.Fn gelf_checksum
provides a class-independent way retrieving the checksum
for ELF object
.Ar elf .
.Sh RETURN VALUES
These functions return the checksum of the ELF object, or zero in case
an error was encountered.
.Sh ERRORS
These functions may fail with the following errors:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar elf
was NULL.
.It Bq Er ELF_E_ARGUMENT
Argument
.Ar elf
was not a descriptor for an ELF file.
.It Bq Er ELF_E_ARGUMENT
The ELF descriptor
.Ar elf
was not opened for reading or updating.
.It Bq Er ELF_E_CLASS
For functions
.Fn elf32_checksum
and
.Fn elf64_checksum ,
ELF descriptor
.Ar elf
did not match the class of the called function.
.It Bq Er ELF_E_HEADER
The ELF object specified by argument
.Ar elf
had a malformed executable header.
.It Bq Er ELF_E_RESOURCE
An out of memory condition was detected during processing.
.It Bq Er ELF_E_SECTION
The ELF object specified by argument
.Ar elf
contained a section with a malformed section header.
.It Bq Er ELF_E_VERSION
The ELF object was of an unsupported version.
.El
.Sh SEE ALSO
.Xr strip 1 ,
.Xr elf 3 ,
.Xr gelf 3
